Modeling the Optical Properties of Conjugated Polymer Assemblies: Interchain Vs. Intrachain Interactions

共轭聚合物组装体光学性质的建模：链间与链间的比较

• 批准号: 1203811
• 负责人: Francis Spano
• 金额: $ 41.78万
• 依托单位: Temple University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-01 至 2016-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1203811&HistoricalAwards=false
• 关键词: Modeling; Optical; Properties; Conjugated; Polymer

This award is funded by the Division of Materials Research and the Chemistry Division. It supports theoretical research and education on the interaction of thin films of pi-conjugated polymers and related oligomers with light. Despite the many experiments designed to uncover the mechanisms by which polymer films interact with light, a global appreciation of the relationship between solid-state morphology and photophysical behavior is still lacking. The H-aggregate model, which has been successful in describing the photophysics of spin-cast poly (3-hexylthiophene) films, nevertheless fails to account for several key photophysical properties of phenylene vinylene- and fluorene-based polymer films, such as the temperature-dependence of the photoluminescence line shape. This award supports research to investigate a more sophisticated polymer aggregate model, the HJ-aggregate model. Unlike the H-aggregate model, the HJ-aggregate model accounts for multidimensional exciton motion, both along and normal to the polymer backbone. Specific goals of this project include: 1) A detailed understanding of how photophysical properties are affected by the competition between interchain interactions, which lead to delocalized Frenkel type excitations and H-aggregate-like behavior, and intrachain interactions, which lead to Wannier-type excitations and J-aggregate-like behavior. The interchain vs. intrachain competition can be understood from the way the vibronic progressions in the absorption and photoluminescence spectra are altered as a function of the exciton coupling along and normal to the polymer chains, the temperature, and the degree of spatially-correlated disorder along and normal to the polymer chains. The vibronic progressions, sourced primarily by the ubiquitous vinyl-stretching mode common to virtually all pi-conjugated molecules, therefore serve as a probe of the exciton bandwidth, exciton coherence length and generalized morphology. Specific applications will be made to poly (3-hexylthiophene) assemblies, which behave as H-aggregates when spin-cast from various solvents, but also as J-aggregates, when self-assembled in a slowly-cooled toluene solution. The possibility of a morphology-driven transition from H- to J-aggregate behavior is not only a fundamental novelty but can be exploited for device optimization. 2) A more complete understanding of exciton coherence in polymer films, with an aim at optimizing coherent transport by taking advantage of the large coherence lengths recently measured in single-chain polydiacetylene. 3) A detailed analysis of conformationally disordered polymer chains, with an aim at understanding how disorder and vibronic coupling conspire to create conformational units and affect photophysical properties. Analyses will be based on Holstein-variety Hamiltonians, treating through-bond and through-space excitonic interactions, linear exciton-vibrational coupling, and disorder on equal footing. Multi-particle approximations will be employed to reduce the basis set to a tractable size for numerical analysis without sacrificing accuracy. Fundamental excitations and their steady-state spectral signatures will be evaluated using standard numerical matrix techniques. NON-TECHNICAL SUMMARY This award is funded by the Division of Materials Research and the Chemistry Division. It supports theoretical research and education on how thin films composed of a class of long chain molecules, polymers, interact with and emit light. The research is focused on key issues that impede understanding of the mechanisms by which these films interact with light, how light is absorbed by these materials and the nature of the electronic states after absorbing light. A key feature of the PI?s approach is to account for the interaction of electronic charge with vibrations of the molecular chains. A thrust of this project is to investigate a new model to describe the behavior of the electrons along molecular chains and between molecular chains. Thin films of particular kinds of polymers may be useful as active materials for organic-based electronic devices such as transistors, light emitting diodes, and solar cells. This research project contributes to the intellectual foundations that will enable the use of these materials for lighting, solar energy conversion, and other electronic devices. The commercial impact of soft electronic devices is expected to dramatically increase over the next several years, through products like flexible displays, electronic labels and solid-state lighting. In addition, the proposed activities will enhance research infrastructure through international collaborations.

该奖项由材料研究部和化学部门资助。它支持理论研究和教育，涉及PI结合聚合物及相关的低聚物的薄膜相互作用。尽管许多实验旨在发现聚合物膜与光相互作用的机制，但仍缺乏对固态形态与光体物理行为之间关系的全球欣赏。 H-聚集模型已经成功地描述了自旋 - 播多（3-己基噻吩）膜的光物理学，但仍未说明苯乙烯乙烯 - 乙烯基和氟聚合物聚合物膜的几种关键光物理特性，例如光摄影线形状的温度依赖性。该奖项支持研究，以调查更复杂的聚合物聚合物模型HJ聚集模型。与H-Aggregate模型不同，HJ聚集模型沿沿聚合物主链和正常的多维激子运动说明了多维激发运动。该项目的具体目标包括：1）对光物理特性如何受到链间相互作用之间的竞争的详细理解，这些链相互作用会导致DELAICALIGAT FRENKEL型兴奋和类似H-聚集的类似于类似于H-凝集的相互作用，以及导致Wannier-type-type-type-type-type兴奋和类似J-Aggregation类似J-Aggregation类似的行为。可以从吸收和光致发光光谱中的振动进展的方式来理解链链与内部竞争，这是沿激情链偶联的函数，并正常与聚合物链，温度以及沿着聚合物链正常的空间相关障碍的程度。振动进展主要是由几乎所有PI共轭分子的普遍乙烯基拉伸模式来源，因此是对激子带宽，激子相干长度和广义形态的探针。将在聚（3-己基噻吩）组件中进行特定的应用，当从各种溶剂中自旋铸造时，它们的表现为H-聚集，但当在缓慢冷的甲苯溶液中自组装时，也将其作为J-聚集体。形态驱动的从H-到J聚集行为的过渡不仅是一种基本新颖性，而且可以利用用于设备优化的新颖性。 2）对聚合物膜中激子相干性的更完整了解，目的是利用最近在单链聚二乙烯中测得的较大的相干长度来优化相干传输。 3）对构象混乱的聚合物链的详细分析，目的是了解疾病和振动耦合如何共同创建构象单位并影响光物理特性。分析将基于荷斯坦 - 杂种哈密顿量，以相等的基础治疗整个键和通过空间的激子相互作用，线性激子 - 振动耦合以及无序。将采用多粒子近似值将基础设置减少到可拖动的大小，以用于数值分析而无需牺牲准确性。将使用标准数值矩阵技术评估基本激发及​​其稳态光谱特征。非技术摘要该奖项由材料研究部和化学部门资助。它支持理论研究和教育，内容涉及一类长链分子，聚合物，与光线相互作用并发出光线的薄膜。这项研究的重点是阻碍对这些膜与光相互作用的机制的理解，这些材料吸收光线以及吸收光后电子状态的性质的理解的关键问题。 PI方法的关键特征是说明电子电荷与分子链振动的相互作用。该项目的一个推力是研究一个新模型，以描述沿分子链和分子链之间的电子行为。特定类型的聚合物的薄膜可能可作为有机电子设备（例如晶体管，发光二极管和太阳能电池）的活性材料。该研究项目为智力基础做出了贡献，这些基础将使这些材料用于照明，太阳能转换和其他电子设备。通过柔性显示器，电子标签和固态照明等产品，预计软电子设备的商业影响将在未来几年内急剧增加。此外，拟议的活动将通过国际合作来增强研究基础设施。